I opted to use a blood orange in this recipe because it is visually stunning and is slightly less acidic than other oranges. Blood oranges are a winter fruit so depending on when you make this recipe, you may need to opt for the slightly less exotic Valencia or navel variety. When selecting oranges, look for ones that are heavy for their size and firm to the touch.

Combine the flour and sugar in a medium bowl and whisk together by hand.

Place the egg yolks in a medium bowl and whisk by hand until blended.

Put the milk in a medium saucepan and bring to a boil over medium heat. Reduce the heat and add the flour mixture. Whisk until the mixture is smooth.

Remove from the heat. Whisk 2 tablespoons of the milk-flour mixture into the egg yolks to warm them slightly.

Carefully add the yolks to the remaining milk-flour mixture.

Place over medium heat and cook, whisking constantly, until the base is the consistency of mayonnaise, 4 to 5 minutes. Remove from the heat. Transfer the base to a large bowl and cover with plastic wrap to prevent a skin from forming. Let cool for 30 minutes.

Put the egg whites in the bowl of a stand mixer fitted with the whip attachment. Beat on medium speed until they start to froth. Increase the speed to high and add the sugar. Beat until the whites start to lose their shine but still look wet. They hill hang in medium-stiff peaks when the whip is lifted from the bowl.

Fold about one-third of the whites into the base with a rubber spatula. Gently fold in the rest of the whites, chopped chocolate and orange filling just until no streaks remain.

Distribute the mixture evenly among the prepared molds, filling them level and smooth with the top. Put the molds on a sheet pan.